Kevinrob\GuzzleCache\CacheEntry::serveStaleIfError PHP Method

    public function serveStaleIfError()
    {
        return $this->staleIfErrorTo !== null && $this->staleIfErrorTo->getTimestamp() >= (new \DateTime())->getTimestamp();
    }

 /**
  * @param CacheEntry|null $cacheEntry
  *
  * @return null|ResponseInterface
  */
 protected static function getStaleResponse(CacheEntry $cacheEntry = null)
 {
     // Return staled cache entry if we can
     if ($cacheEntry instanceof CacheEntry && $cacheEntry->serveStaleIfError()) {
         return $cacheEntry->getResponse()->withHeader(self::HEADER_CACHE_INFO, self::HEADER_CACHE_STALE);
     }
     return;
 }